Launched in 2006 at the Basel Fair, the wristwatch houses Patek Philippes first in-house chronograph caliber and sets the stage for future development using caliber 28-520. In its current form, as used in Ref. 5960P, it has an annual calendar combined with hour and minute recorder on the same subsidiary dial. The two times 30-minute register is used in conjunction with the aperture at the 6 o'clock position indicating if the minutes are in the first or second 30.